Browsing by Author "Osypenko, Iryna O."

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    Advanced Space Vector Modulation with “Fractional” Power Cells
    (Elsevier B.V., 2025) Busher, Victor; Shestaka, Anatoliy; Melnikova, Lubov; Kuznetsov, Vitaliy V.; Mykhailenko, Oleksii; Kovalenko, Viktor; Kutyk, Viktor; Osadchyi, Dmytro; Osypenko, Iryna O.; Abdel Gawad, Samer
    ENG: The paper develops a model and studies various operating modes of a 5-phase multi-level cascade inverter as part of high-voltage powerful variable-frequency drives (VFD) with the most typical fan load for this type of electric drives. The aim of the work is to test the efficiency of the balanced spatial-vector pulse-width modulation method in a multi-phase high-voltage multi-level inverter in emergency modes by simulating the electric drive in the MATLAB/SIMULINK/Simscape Electrical environment. The paper studies the features of using the balanced spatial-vector pulse-width modulation method in a five-phase frequency converter in normal and emergency modes and, especially, the differences from a three-phase inverter with a similar control principle. The model with a 5-phase synchronous motor from the MATLAB ac8_example.slx database is taken as a basis, which allows us to consider the simulation results reliable. The rules for calculating phase voltages in normal and emergency modes are formulated and the corresponding blocks of the inverter control system model are prepared - a block for calculating basic vectors and a block of spatial vector pulse-width modulation (PWM). The output signals of this block are used for further processing in the modules for controlling power cells with 2- or 3-level PWM. Such a model for a 5-phase electric drive has been built for the first time, which is a scientific novelty of the work. Calculations of transient processes showed the absence of any oscillations, shocks when the system switches from normal to emergency mode and vice versa. That is, the proposed method of balanced spatial vector modulation preserves the symmetry of electromagnetic fields in the engine when individual H-bridges are damaged. It is shown that in normal mode, a 5-phase inverter using the spatial vector modulation method allows increasing the utilization factor of voltage sources by 23.1%. When individual power cells in phases fail, the utilization factor may decrease, but in any case it remains greater than 1. The method ensures compensation for emergency damage even in the event of a short circuit of one or two inverter phases. This significantly increases the service life of the electric drive, which is especially important in critical mechanisms and technological processes, where such complex inverters are actually used. The study found that when using the proposed method in a 5-phase VFD, unlike a 3-phase one, the current balance in the load is disrupted, which leads to increased heating of individual phases of both the motor and the power section of the inverter. The second point of scientific novelty of the work is that in order to reduce this negative effect, it is proposed to improve the algorithm for calculating the output coordinates of the regulator by using the so-called “fractional” power cells with a voltage that is not a multiple of their rated voltage. This leads to a smooth change in phase shifts and asymmetry when individual H-bridges and even one or two phases are damaged. This, in turn, reduces the current imbalance and the corresponding overheating from 2...3 to 12...15%, which gives confidence in the efficiency of using this improvement. It is also important to note that such a change in the control algorithm does not require any changes in the circuit and does not increase the requirements for the computing power of the processors used.
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    Construction of a Kinetic Equation of Carbon Removal for Controlling Steel Melting in the Metallurgical System "Cupola Furnace – Small Converter"
    (TECHNOLOGY CENTER PC, Kharkiv, 2025) Makarenko, Dmytro M.; Selivorstova, Tetiana V.; Dotsenko, Yuriy V.; Osypenko, Iryna O.; Dzevochko, Oleksandr M.; Pereverzieva, Alevtyna M.; Dzevochko, Alona I.
    ENG: The object of research in the paper is the process of steelmaking in a small converter, which works in tandem with a cupola furnace. The existing problem is that the control of the process of obtaining steel in an oxygen converter is complicated by the need to determine in real time the current chemical composition of the melt, in particular carbon. This is due to the fact that the rate of carbon removal is too high, as a result of which the process of carbon removal is transient. Therefore, it is too difficult to implement regulation based on feedback on continuous measurement. The presence of the specified problem requires solutions related to the possibilities of developing or improving software control of the process. It is shown that in certain sections of the process within each time section of oxygen purging of the melt in the converter, the kinetic curve has a linear form with a constant coefficient value in front of the inlet mine. But the value of the initial coefficient for each equation that describes the process within its limits changes. This allows to state that in case of a change in the initial condition, the kinetic curves shift relative to each other in parallel. On this basis, a system of equations has been constructed that describes the process of carbon removal in a small oxygen converter that receives liquid iron from a cupola furnace. It has been shown that to use the obtained system of equations, it is necessary to know the initial carbon content in the melt discharged from the cupola furnace, and it depends on the method of oxygen supply to the cupola furnace. Based on the modeling of this process in two variants – using a “sharp blow” and supplying oxygen to the air blown into the tuyeres, a nomogram has been constructed. It allows to determine the initial carbon content for the practical use of the obtained system of equations. Using the obtained system makes it possible to determine the time after which oxygen cutoff should be made. This will allow to decide to implement software control of the melt blowing process in the converter. The presented study will be useful for machine-building enterprises that have foundry shops in their structure, where cast iron is smelted for the manufacture of castings.